1. Field of the Invention
This invention relates to the field of data backup software for computer systems. More particularly, the invention relates to a system and method for implementing time-based checkpoint intervals for a backup operation.
2. Description of the Related Art
Computer systems often use backup software to backup data in order to protect the data against hardware failure or data corruption. Data may be stored on a storage device or in a logical volume of the computer system in the form of files. Backup techniques for backing up the files generally operate to create a backup image. One general backup technique is to backup the files at the file level, e.g., to include the files in the backup image on a file-by-file basis. In this technique, all the data for a given file is typically stored in the backup image, followed by all the data for the next file, etc. Another general backup technique is to backup the backup the files at the storage device block level rather than on a file-by-file basis. In this technique, the blocks may be sequentially read from the disk drive or other storage device on which the volume is stored and written to the backup image.
The backup image may be used to restore the data to the computer system in the event that it becomes necessary to do so, e.g., if the storage device on which the data is stored fails, if the data becomes corrupted, or if a user or software application needs to access the data is it existed at the time the backup image was created.
Large amounts of data may take a significant amount of time to backup. Failures sometimes occur during a backup operation so that the backup operation is interrupted before all of the data is backed up. In the case of a failure, the backup operation may be re-started. In order to avoid the need to re-start the entire backup operation from the beginning, the backup software controlling the backup operation may create checkpoints at various points during the backup operation. If the backup operation fails then it may be re-started from the most recent checkpoint. Thus, the data that was backed up before the most recent checkpoint was created does not have to be backed up again.